GitHub user kinow opened a pull request:
https://github.com/apache/commons-collections/pull/28
COLLECTIONS-661: fix for concurrency issue in HashSetValuedHashMapTest
The `getMap()` method, when testing a `HashSetValuedHashMap`, would return
an object of this type. Which is an instance of `SetValuedMap`.
Running it in debug mode would - most of the times - run the tests and
succeed. Running normally - especially on Windows - would result in
intermittent, but very frequent, failures.
The `getMap()` method sometimes, depending on the order and execution of
tests, will be null. So the collection added to the map will be either a
`Hashset`, or a `Arrays$ArrayList`. When the types are different, `hashCode()`
and `equals()` calls return incorrect values, resulting in the errors we have
seen in COLLECTIONS-661.
A good solution would be to re-design the tests. The
`TestMultiValuedMapAsMap` is testing `MultiValuedMap`'s, which include
`HashSetValuedHashMap`. However, some of its methods contain extra logic for
when the type under test has some characteristics like being an instance of
`SetValuedMap`.
It might be possible to come up with a better design, where there are
multiple test classes, for `MultiValuedMap`'s that use `SetValuedMap`'s;
`MultieValuedMap`'s that use `List`'s, and so it goes.
Or we could add a class to the parent class, with a flag defining the type
under test. For now, I have used the `makeObject()` method, which returns the
collection under test. Then I validate its instance type. There is also a
comment above the code to indicate why we are using `makeObject()` and not
`getMap()`.
It was a fun ticket. Happy to get feedback on better solutions, or feel
free to edit this pull request if you have right to it, or merge if you are
happy and it has gathered some consensus.
Cheers,
Bruno
You can merge this pull request into a Git repository by running:
$ git pull https://github.com/kinow/commons-collections COLLECTIONS-661
Alternatively you can review and apply these changes as the patch at:
https://github.com/apache/commons-collections/pull/28.patch
To close this pull request, make a commit to your master/trunk branch
with (at least) the following in the commit message:
This closes #28
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commit 6e8951ed0325abe3e07e32aded0b27aacdbc1011
Author: Bruno P. Kinoshita <[email protected]>
Date: 2017-10-11T07:27:25Z
COLLECTIONS-661: fix for concurrency issue in HashSetValuedHashMapTest
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